Gardening Articles: Landscaping :: Trees, Shrubs, & Vines

The Impact of Climate Change on Colorful Fall Foliage

by Susan Littlefield

New England hillsides are beginning to blaze up in their much-anticipated seasonal display of reds, oranges, yellows. Unfortunately in the Northeast and other parts of the country, this autumnal show may not be as spectacular in the future, as global climate change disrupts weather patterns.

While maples may still don their fall colors, the change may happen later in the season, and the red leaf hues could be duller as the climate warms, according to Howie Neufeld, professor of plant physiology at Appalachian State University in North Carolina.

A 22-year observational study at Harvard Forest in Massachusetts showed that the fall foliage color change there now occurs three to five days later, on average, than it did at the beginning of the study. This might not seem like much, but if the pattern continues, the timing of color change could shift to well over a week later by mid-century, according to Harvard emeritus professor John O'Keefe, who collected the data.

Cool fall nights and decreasing day lengths are a signal to trees manufacture anthocyanins, the red pigment that colors fall leaves. If nights remain hotter as the climate warms, this process may be disrupted, resulting in less colorful foliage. If droughts become more pervasive, as many climate change models predict, stressed trees may simply shed their leaves early with any color change. Perhaps the biggest worry is that climate change will make conditions unsuitable for trees such as sugar maples, forcing them to migrate north to survive. None of the more southerly species that might move in to replace them have the brilliant fall colors that maples display.

To read more about why autumn leaves may be dulled by climate change, go to Vermont Invasives